I recently came into possession of a Besson 3 Valve Compensating Bbb Tuba that needs a little work, but is overall in fair, playable condition. I tried looking up the model numbers in the links provided on this site, and either there's a gap, or I'm not smart enough to figure out what's going on.
Here's the info on the horn:
SN: 457780
Bell Engraving: "50 Medals of Honour (in a banner) B Besson (star under Besson) London-Paris-New York Made in England" Also there is an "H" above the two on the second valve, which maybe indicates High Pitch, but I don't think the horn is that old.
Apart from that there is a bearing ball (not sure what to call it) on the bottom bow, which most newer (60s forward) horns don't tend to have.

Any help would be appreciated as to determining model and approximate year of manufacture, as I do need a new water key on the first valve slide - right now I'm using a water key cork glued to a bit of rubber band.

Thanks in advance!